Method of and means for indicating a chosen area



April 24, 1951 M, SWANSON' 2,549,860

METHOD oF AND MEANS FOR INDICATING A cHosEN AREA Filed sept. 1o, 193e H g /Z /5 5 Q5 F1 g. l /a Patented pr. 24, 1951 METHOD OF AND MEAN S FOR INDICATING A CHOSEN AREA v Mark Swanson, Washington, D. C. Application September 10, 1936, Serial No. 100,177 12 Claims.` (Cl. 343-108) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) This invention relates to a method of and means for indicating, by radiant energy, the position and bounding limits of a chosen area, more particularly an aircraft landing field or the landing deck of a carrier obscured by darkness or fog.

Among the objects of this invention' are:

To provide a means and method for utilizing infra-red rays or very short radio rays to indicate theposition and limits of a given area;

To provide means to insure the safe handling of aircraft While landing upon fogbound or darkcned airports or the decks of aircraft carriers.

To provide means of the type specied that will be invisible except when detected by suitable receiving devices;

To provide normally invisible means that wiil enable a pilot to establish his exact position with respect to runways and his elevation thereabove.

In the drawings:

Fig. 1 is a top plan View illustrating the relation of the sources of radiant energy with respect to a chosen area whereof the position is to be defined;

Fig. 2 is a side elevational view of the same but with the addition of a beam defining a known elevation above the area.

Fig. 3 is in general similar to Fig. 1 but indicates the path that may be followed by a pilot in landing under the guidance of the radiant energy beams;

Fig. 4 shows a side view of the path followed by a pilot in landing; Y

Fig. 5 illustrates the indication received by the pilot at thevarious positions indicated in Figs. 3 and 4 at the points designated by letters corresponding to the'letters indicating the several parts of Fig. 5; l

Fig. 6 shows schematically one form of detector for use of infra-red rays;

Fig. 7 likewise illustrates a receiver but in'which the image is inverted in one direction 'by reneetion.

The principle and the mode of use of my invention will be set forth and illustrated by reference to beams of infra-red light, but it is also contemplated that radio beams ofI ultra high frequency (micro-waves or quasi-optical waves), which behave in many respects like light, may be used. Further, while particular reference is herein made to landing areas for aircraft, it is to be understood that the usefulness thereof extends to the indication of areas for other purposes. It

will be obvious to those skilled in this art thaty when micro-waves are used the separate beams will be detected by apparatus of known construction tuned to the vfrequency of the particular beam.

In Fig. l the chosen area 8 is provided at one end with sources 9, I and I I that project beams I2, I3 and I4, respectively,.of radiant energy along the chosen area 8. The sources 9' and I0 are soy adjusted that, as viewed in the direction of propagations -of the beams, the left-hand edge 2 of beam I2' is parallel to and substantially coincides with the left-hand edge of area 8, while the right-hand edge of beam I3 has a like relation to the right-hand edge of the area, the other edge of each beam extending beyond the respectively opposite edge of the area 8, thus forming an overlapping zone I5 of substantially the width of the area 8 and in alinement therewith, wherein both the sources 9 and I0 may be detected, but beyond which and within the limits of either beam but one thereof may be detected. The source II is so adjusted that the upper edge thereof, as seen in Fig. 2, is substantially parallel to the surface of area 8 at a known distance above that surface. It will be noted from the relative position of source I I with respect to sources 9 and IU that the beam I4 lies within the horizontal limits of beams i2 and I 3 but that the beams I2 and I3 are pro-v jected upwardly at an angle to permit the same to be. detected while at a safe elevation above the area and that there is a zone I6 above the area andv within the vertical planes bounding the same that is common to all three beams.

When using infra-red rays they may be detected due to the extinguishing or intensifying eiect of infra-red light upon luminescence. It is apparent, however, that the luminescent material must show under infra-red stimulus practically no time lag, that is, it must be practically instantaneously excitable and extinguishable under infra-red stimulus due to the fact that the infrared sources, when viewed from a rapidly moving aircraft, would appear as lines rather than spots if there were persistence of luminescence. The luminescent material I use has the desired characteristics to a higher degree than any heretofore known that I was able to procure. It consists of a sulphide of either an alkaline earth metal or zinc with a minute percentage of manganese or rhenium as the activatingV impurity.`

This material and a method of preparing the same are fully disclosed in my copending application, Serial No. 100,178, filed September 10, 1936, U. S. Patent No. 2,396,298; issued March 12, 1946.

The detector shown in Fig. 6 comprises a luminescent screen Il irradiated by ultra-violet light from a. suitable source I3 which may be a small argon glow lamp with a lter for preventing ,the passage of other than the long4 wave length ultra-violetrays. The lens I9 and window 20 are of glass such as that known to the trade as Corning No. 254, that will pass infra-red rays. It will be observed that the lens I9 will give an image that is inverted in all planes. The infrared light sources appear on the screen I1 as very bright yellowish or whitish-yellow spots and thus the normally invisible radiation is translated into visible light, which contrasts strongly with the ultra-violet light.

The form of detector shown in Fig. 7 is in gene:

3 eral similar to that of Fig. 6 except that aV mirror 2I, set at an angle of 45 to the light vcoming through lens I9 and also to the surface of screen I1 erects the image in one plane. The detecting elements in both Figs. 6 and '7 4are -lziousedv in a light-proof inclosure 22.

The method of landing an aircraft under the guidance of the system of beams above described will now be set forth. The pilot will'know in general the position of the area 8 and will s028913 his course as to enter one or moreof the beams I2, I3 and I4. In Figs. 3 and 4 his path is in.- dicated as coming intothe beams from above and from theleft, as viewed by the pilot. If he is using the detector shown in Fig. 6, when he has reached the point A he will perceive the image of the source 9 in the lower right-hand cornerof` screen Il as shown Vat A in Fig. 5, in.- dicating his plane is headedlohgitudinally to the right of area 8 with nose down. When vhe has reached the point B he will perceive both the sources .9 and ill as indicated at B in Fig. 5, due to the fact that he is in the ccmmcnzone I5 and he then knows that his position is alined with the area -8 but he is still headed to the right Yof 8. However, his flight direction continues him across the zone I and when at point C he will perceive the source Ii] as shown at C in Fig. Hev then' swings back to the left to reenter the commonzone I4 and again picks up .both of sources y9 and I il .as indicated at D in Fig. 5. This shows he is centrally located over area .8 with nose slightly down. He noses down to lose altitude and enters the zone `IIE common to all three beams, when the appearance on the screen .is as shown at E of Fig. 5, and he knows that heis then at an altitude less than .that indicated by the upper limit or" beam I4 and within -the vertical planes bounding area 8 sche continues .to lose altitude and land, the appearance on the .screen at the points F (leveling-off and raising nose) and G @(nose up, tail down) in Figs. 3 and 4 being as indicated at Fand G in Fig. 5. When within the beams l2 and i3, the lateral position .of .the plane is evident. Departure from lateral position is vobvious from angular displacementof the.hori. zontal images with respect to the screen.

When micro-waves are used instead of invisible light a suitable reflector to direct those waves into .a beam wil-l be used in connection with .each transmitter and a separate receiver provided with an indicator will be tuned Vto .the respective fre-v quency -o-f each of the transmitters so that the indication of lany given receiver willvshowvthat the craft is with-in the beam of the transmitter to which the receiver is tuned. The apparatus for transmitting and receiving Amicro-waves is known in the art Yand is therefore not illustrated blltit iswell adapted forl practicing my method.

The invention herein described and claimed may be used and/'or manufactured by or for the Government ofthe United 'States Aoi America for governmental purposes without the payment of any royalties thereon or therefor.

.IY claim;

l. A system as described, comprising means for projecting :two laterally overlapping beams of invisible radiant energy that includes infra-red light, said beams having their upper and lower limits substantially in .common respective tra-ns,A

verse pla-nes and -a lateral limit of each beam substantially dening a corresponding lateral boundary of .a selected area, other mea-ns ,for project--l ing a like beam lying between said :lateral boundarles but so directed vout of said common zone of fthe other beams :that 'the loverlapping of thebeam-fr0m the last mentioned means upon the other said beams terminates substantially at vthe terminus of said area, and means to detect said infra-red .component including a screen .coated with substantially instantaneously responsivelu-minescent material, a source of ultraviolet light to irradiate said screen to excite luminescencethereon, and means to project on said screen'the images of all of said projecting means Within the field of said detecting means, said images being rendered visible on said screen by the effect of the infra-red light upon said lumlleSQe/Xlce- 2- A, system .as described, comprising means fOr projecting two laterally Overlapping beams QI radiant energy, said beams having their upper and lower limits suhtantally in common respective transverse planes and a lateral limit of each beam substantallv defining a corresponding lateral boundary of a selected area, other means for projecting a like beam lying between said lateral boundaries but N so `directed out of the said common zone that the overlapping oi' .the beam from the `last mentioned means upon the `other said beams terminates substantially at the terminus of .said area, and receiving lmeans to detect l and distinguishingly identify saidbeams.

3. A system as described, comprising ymtans for projecting a pair of laterally overlapping beams of radiant energy at ,an angle above the horizon with one lateral limitof .each defining the corresponding edgeof a chosen area but the other lateral .limitof each extendingbeyond the f edge .of the area corresponding thereto, whereby arzene .common Yto the .two rloelrrls lies between vertical planes at ,the lateralboundaries of saidv area, means to project a third beam ingeneral below the other` said beamsvbu-t having in common therewith a zonelying within vertical planes bounding said area, and receiving means to de tect and distinguishingly identify all of the beams lying within the field of said receiving means.

4. A system as described, comprising I-neansV for projecting .a pair yof lateral-ly overlapping beams of radiant lenergy at an angle above the horiZQn with vone .lateral limit of each defining the corresponding edge of a chosen area but the other lateral limit of each extending beyond :the edge .of the area corresponding thereto, whereby a rone common to the two-beams lies between vertical yplanes at the lateral boundaries of .sa-id area, means to prejet athird beam :in .ige-neral. below the other said beams with its upper limi-t substantially horizontal but having :in common therewith `a zone lying Within vertical planes.-

beyond the lateral boundary .opposite theretd.

there being `thus a zone vcorri-mon to the two beams, means `to project a third like beams-with its upper limit substantially horizontal and hav.- ing a zone common with the saidbeams, the said zone common to all :three beams "lying witinn were tical planes 4bounding said area, and means for receiving said infra-red .liebt and'renderingfthe same visible while indicating, fby the relative position. said recevihsfmeansfofethezlight ,rene Y.

limit of each beam extending beyond the correi spondingly opposite side of the area, the said beams overlapping and having a common zone alined with and substantially the width of said area, projecting a third like beam with the upper limit thereof substantially parallel to the surface of said area and having a zone in common with the other two beams within vertical planes bounding said area, and converting said infrared light into Visible light to identify the positional significance of all beams in the eld of detection, whereby the aircraft pilot so identifying said beams may cause his craft to enter the zone common to all three beams and land therein.

7. A method of indicating the location and limits of an obscured landing area for aircraft, comprising the steps of projecting at an angle above the horizontal, two beams havingat least a component in the infra-red, one lateral limit of each beam substantially coinciding with a corresponding side of said area, the said beams overlapping and having a common zone alined with and substantially the width of said area, projecting a third like beam with the upper limit thereof substantially parallel to the surface of said area and having a zone in common with the other two beams within vertical planes bounding said area, and converting said infra-red light into visible light to identify the positional significance of all beams in the eld of detection, whereby the aircraft pilot so identifying said beams may cause his craft to enter the zone common to all three beams and land therein.

8. A method of indicating the location of an obscured landing area for aircraft, comprising the steps of so projecting two beams of invisible radiant energy at an angle above the horizontal that one lateral limit of each beam substantially coincides with a corresponding side of said area while the other lateral limit of each beam extends beyond the correspondingly opposite side of said area, the said beams thus overlapping and having a common zone alined with and substantially the width of said area, projecting a third like beam with the upper limit thereof substantially parallel to the surface of said area and having a zone in common with the other two beams within vertical planes bounding said area, and detecting said energy to determine the positional significance of all beams in the field of detection, whereby the aircraft pilot observing the indication of said detected energy may cause his craft to enter the zone common to all three beams and land therein.

9. A method of indicating the location and limits of an obscured landing area for aircraft, comprising the steps of projecting, at an angle above the horizontal, two beams having at least a component in the infra-red, one lateral limit of each beam substantially coinciding with a corresponding side of said area, the other lateral limit of each beam extending beyond the correspondingly opposite side of the area, the said beams overlapping andv having a common zone alined with and substantially the width of said area, and projecting a third like beam with the upper limit thereof substantially parallel to the surface of said area and having a zone in common with the other two beams within vertical planes bounding said area.

10. A method of indicating the location of an obscured landing area for aircraft, comprising the steps of so projecting two beams of invisible radiant energy at an angle above the horizontal that said beams have in common a zone of substantially the width of said area alined with said area to define the lateral limits and the azimuthal orientation of said area, and projecting a third like beam to have in common with the said two beams a portion of said common zone lying within vertical planes bounding said area and to indicate an altitude above the surface of said area.

11. A method of indicating the location of an obscured landing area for aircraft, comprising the steps of so projecting two beams of radiant energy at an angle above the horizontal that one lateral limit of each beam substantially coincides with a corresponding side of said area while the other lateral limit of each beam extends beyond the correspondingly opposite side of said area. the said beams thus overlapping and having a common zone alined with and substantially the width of said area, projecting a third like beam with the upper limit thereof substantially parallel to the surface of said area and having a zone in common with the other two beams within vertical planes bounding said area, and detecting said energy to determine the positional significance of all beams in the field of detection, whereby the aircraft pilot observing the indication of said detected energy may cause his craft to enter the zone common to all three beams and land therein.

12. A method of indicating the location of an obscured landing area for aircraft, comprising the steps of so projecting two beams of radiant energy at an angle above the horizontal that said beams have in common a zone of substantially the width of said area alined with said area to define the lateral limits and the azimuthal orientation of said area, and projecting a third like beam to have in common with the said two beams a, portion of said common zone lying within vertical planes bounding said area and to indicate an altitude above the surface of said area.

MARK SWANSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date France June 23, 1924 Great Britain Apr. 27, 1933 Great Britain Apr. 9, 1934 OTHER REFERENCES The Colloidal Salts,` by Weiser, 1st ed., page 164, published by McGraw-Hill, 1928,

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